A test device, for checking the functioning capability of a gas-alarm annunciator, has a reservoir in which are located a target fluid and a carrier fluid. At least a part of the carrier fluid is present in a liquid aggregate state and the target fluid is at least partially dissolved in the liquid carrier fluid. An extraction device engages into the reservoir such that the target fluid can be extracted along with the liquid carrier fluid. The target fluid is constituted such that on reaching a coverage area of a properly functioning gas-alarm annunciator it will cause the gas-alarm annunciator to annunciate an alarm. A test system and a test method for checking a gas-alarm annunciator's functioning capability use such a test device.